SHANGHAI, April 19 (Reuters) - China and Hong Kong stocks extended gains on Thursday, helped by robust gains in resources firms, as rising oil prices aided a rally across commodities. ** The CSI300 index rose 1.3 percent to 3,815.55 at the end of the morning session, while the Shanghai Composite Index gained 1.0 percent to 3,121.51. ** The Hang Seng index added 1.3 percent to 30,672.29, while the Hong Kong China Enterprises Index gained 2.1 percent to 12,242.19. ** Sectors rallied across the board, led by materials and energy firms. ** Oil prices on Thursday remained close to late 2014-highs reached in the previous session as U.S. crude inventories declined and as top exporter Saudi Arabia pushes for prices of $80 to $100 per barrel by continuing to withhold supplies. ** The surge came on a Reuters report that OPEC’s new price hawk Saudi Arabia would be happy for crude to rise to $80 or even $100, a sign Riyadh will seek no changes to a supply-cutting deal even though the agreement’s original target is within sight. ** In the metals market, aluminium hit its highest in nearly seven years on Wednesday amid growing supply concerns in the aftermath of U.S. sanctions on Rusal, while nickel hit a three-year peak on technical factors and fears over additional Russian sanctions. ** Metals producers jumped on the mainland and Hong Kong, with China’s largest aluminium producer Chalco leaping 8.6 percent in Shanghai. ** An index tracking material firms in Hong Kong climbed 3.9 percent, and was poised for its best day since early February. ** Around the region, MSCI’s Asia ex-Japan stock index was firmer by 0.85 percent, while Japan’s Nikkei index was up 0.37 percent. ** The yuan was quoted at 6.2666 per U.S. dollar, 0.13 percent firmer than the previous close of 6.2745. ** The largest percentage gainers on the main Shanghai Composite index were China National Software & Service Co Ltd up 10.01 percent, followed by Shanghai East-China Computer Co Ltd gaining 10 percent and Sino-Platinum Metals Co Ltd up by 9.98 percent. ** The largest percentage losers on the Shanghai index were Shanghai U9 Game Co Ltd down 7.45 percent, followed by Anyuan Coal Industry Group Co Ltd losing 4.92 percent and Henan Huanghe Whirlwind Co Ltd down by 3.89 percent. ** The top gainers among H-shares were Guangzhou Automobile Group Co Ltd up 6.51 percent, followed by PetroChina Co Ltd gaining 5.34 percent and CGN Power Co Ltd up by 4.9 percent. ** The three biggest H-shares percentage decliners were Shenzhou International Group Holdings Ltd which fell 0.59 percent, China Mobile Ltd which lost 0.1 percent and China Gas Holdings Ltd down by 0.2 percent. ** As of 04:08 GMT, China’s A-shares were trading at a premium of 21.97 percent over the Hong Kong-listed H-shares.